Method of manufacturing an analytical sample and method of analyzing an analytical sample

ABSTRACT

A method of manufacturing an analytical sample by a secondary ion mass spectrometry method is provided, which comprises a step of forming a separation layer over a substrate, a step of forming one of a thin film and a thin-film stack body to be analyzed over the separation layer, a step of forming an opening portion in one of the thin film and the thin-film stack body, a step of attaching a supporting body to one of a surface of the thin film and a surface of a top layer of the thin-film stack body, and a step of separating one of the thin film and the thin-film stack body from the substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to a method of manufacturing ananalytical sample. In specific, the present invention is related to amethod of manufacturing a SIMS sample.

2. Description of the Related Art

In production of industrial products, such as semiconductor devices, itis important to see concentration distribution of elements in the depthdirection. For example, in a semiconductor element mounted over asemiconductor device, such as a field effect transistor (hereinafterreferred to as a FET) or a thin film transistor (hereinafter referred toas a TFT), which is a kind of an FET; whether conditions of impurityintroduction is suitable or not can be studied according to theconcentration distribution of impurities in an impurity region in asemiconductor layer.

As a typical analysis method to reveal concentration distribution in thedepth direction, secondary ion mass spectroscopy (hereinafter referredto as SIMS), auger electron spectroscopy (hereinafter referred to asAES), and X-ray photoelectron spectroscopy (hereinafter referred to asXPS) can be given. These analysis methods differ from one another indetection sensitivity, element discrimination capability, and the like;therefore, they are selected in accordance with the purpose. SIMS is ananalysis method which is especially excellent in detection sensitivityand element discrimination capability.

In SIMS, a solid sample to be analyzed is irradiated with primary ionsso that a surface of the solid sample is sputtered, and thus, ionizedmolecules or atoms are emitted from the solid sample surface and theseionized secondary ions are detected with a mass spectrometer. When aSIMS method is used, the concentration of impurity elements in a solidsample in which a thin film is formed on one main surface of a substrateand impurity elements are added to the thin film by ion implantation orthe like, such as a TFT formed over an insulating substrate, can beanalyzed. However, in analyzing such a solid sample, when the solidsample is irradiated with primary ions from a surface side of a thinfilm, the thin film is sputtered by primary ions, so that a crater isformed and the shape of the surface changes with time. Secondary ionsare detected from side surfaces of a crater by a shape effect generateddue to change in surface shape with time (crater edge effect);accordingly, accuracy of data in the depth direction decreases.Therefore, it is preferable to irradiate a rear surface (where a thinfilm is not formed) of a solid sample with primary ions instead of afront surface (where the thin film is formed) of the solid sample inorder to precisely analyze the dose of impurity elements for impartingone conductivity in the thin film of the solid sample. To analyze asample in such a manner, a following method may be employed: a surfaceof the top layer of an analytical sample is fixed to a table forpolishing and a substrate is processed by polishing from a rear surfaceside by chemical mechanical polishing (hereinafter referred to as CMP)and the like to be as thin as about 1 μm, then the rear surface side ofthe substrate is irradiated with primary ions so as to be analyzed bySIMS.

SIMS analysis usually needs a structure which is not affected by chargebuild-up. Therefore, a material which is not electrically charged (e.g.,silicon wafer) is necessarily laid under a film to be analyzed so thatthe film to be analyzed is not at a floating potential. Further, even inthe case of using an insulating substrate, such as a glass substrate, ifexcessive charge build-up does not occur, the use of a neutralizationgun provided for electrical neutralization (e.g., electron gun) allows asample to be analyzed.

A polishing apparatus, such as a CMP apparatus is used for polishing therear surface of the substrate. A CMP apparatus is provided with apolishing pad, a holding head (a head for fixing a sample), and a slurry(which contains a powder for mechanical polishing). As conditions forpolishing, there are a load (force applied vertically to a polishingsurface (a contact surface between the polishing pad and the holdinghead)), rotating speed, and the kind of the slurry, and these conditionsare not easily determined. For example, it is difficult to polish thesubstrate to be as thin as about 1 μm while keeping the sample flat,which may need skills along with a wealth of experiences. In addition,the amount of polishing per unit time is reduced and polishing isconducted carefully, the time required is increased.

As described above, a method in which a rear surface of a substrate ispolished and the polished surface is irradiated with primary ions foranalysis by SIMS are troublesome for processing by polishing, and needsa great deal of time for pretreatment when many samples are evaluated.Further, advanced skill is needed for processing by polishing.Furthermore, flatness of the substrate may be lost due to the polishingstep described above, which brings problems in precision in analysis bySIMS (e.g., see Patent Document 1: Japanese Published Patent ApplicationNo. H9-210885).

SUMMARY OF THE INVENTION

As described above, in a method in which a rear surface of a substrateis polished and the polished surface is irradiated with primary ions foranalysis by SIMS, the substrate is polished with a CMP technique or thelike; accordingly, a large amount of time is consumed to process ananalytical sample. In addition, advanced skill is needed to determineconditions of polishing to polish the analytical sample with uniformityand flatness thereof being kept. Thus, although a method in which a rearsurface of a substrate is polished and the polished surface isirradiated with primary ions for analysis by SIMS enables more preciseanalysis than conventional SIMS in which a front surface is irradiatedwith primary ions, there is a problem in that an analytical sample isnot easily manufactured.

In accordance with the foregoing, it is an object of the presentinvention to provide a method of manufacturing an analytical sample, anda method of SIMS which can be easily and more precisely carried out ascompared with a conventional method.

One mode of the present invention is a method of manufacturing ananalytical sample, which includes forming a thin film or a thin-filmstack body to be analyzed over a substrate, attaching a supporting bodyto the outermost surface of the thin film or the outermost surface ofthe top layer of the thin-film stack body, and separating the thin filmor the thin-film stack body from the substrate.

Another mode of the present invention is a method of manufacturing ananalytical sample, which includes forming a separation layer over asubstrate, forming a thin film or a thin-film stack body to be analyzedover the separation layer, attaching a supporting body to the outermostsurface of the thin film or the outermost surface of the top layer ofthe thin-film stack body, and separating the thin film or the thin-filmstack body from the separation layer.

Another mode of the present invention is a method of manufacturing ananalytical sample to be analyzed by a secondary ion mass spectrometrymethod, which includes forming a separation layer over a substrate,forming a thin film or a thin-film stack body to be analyzed over theseparation layer, attaching a supporting body to the outermost surfaceof the thin film or the outermost surface of the top layer of thethin-film stack body, and separating the thin film or the thin-filmstack body from the separation layer.

The method of manufacturing an analytical sample which is describedabove may further include forming a relief layer between the separationlayer and the thin film or the thin-film stack body which is to beanalyzed.

In the present invention described above, a film with a higher fluorineconcentration than the relief layer is preferably used as the separationlayer.

In the present invention described above each of the separation layerand the relief layer is preferably a film with a fluorine concentrationof 1×10¹⁷ atoms/cm³ or more and 2×10¹⁹ atoms/cm³ or less, a hydrogenconcentration of 1×10²¹ atoms/cm³ or more and 1×10²² atoms/cm³ or less,a carbon concentration of 1×10¹⁵ atoms/cm³ or more and 2×10¹⁸ atoms/cm³or less, a nitrogen concentration of 1×10¹⁸ atoms/cm³ or more and 1×10²⁰atoms/cm³ or less, and an oxygen concentration of 1×10¹⁵ atoms/cm³ ormore and 1×10¹⁹ atoms/cm³ or less is preferably formed.

In the present invention having any of the foregoing structures, thesupporting body preferably has a base material and an adhesive providedon one main surface of the base material, and the adhesive is preferablyformed of a silicone-based adhesive.

In the present invention having any of the foregoing structures, anamorphous silicon film containing fluorine is preferably formed as theseparation layer.

Note that a silicone-based adhesive is an adhesive which containsorganopolysiloxane as its main component. Since silicone includes a Si—Obond, it is similar to an inorganic high molecular compound; however,silicone behaves like an organic high molecular compound due to anorganic group bonded to Si (e.g., a methyl group or a phenyl group).

According to the present invention, concentration distribution in thedepth direction in a target analyte can be analyzed highly preciselywithout a complicated technique.

According to the present invention, a polishing step like CMP is notnecessarily carried out, which is needed in a SIMS method in which arear surface of a substrate is polished and the polished surface isirradiated with primary ions for analysis. Therefore, the time, cost,and the like which are consumed by polishing in a method in which a rearsurface of a substrate is polished and the polished surface isirradiated with primary ions for analysis by SIMS can be saved. Sincetime is not consumed by polishing, concentration distribution in thedepth direction can be analyzed in a short time as compared with aconventional method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an analytical sample manufacturedaccording to the present invention;

FIGS. 2A to 2D are diagrams illustrating a manufacturing process of ananalytical sample according to the present invention;

FIG. 3 is a schematic diagram of a capacitively coupled plasma CVDapparatus for forming a silicon film according to the present invention;

FIGS. 4A to 4C are schematic diagrams of an analytical samplemanufactured according to the present invention;

FIGS. 5A and 5B are diagrams illustrating manufacturing steps of ananalytical sample according to the present invention;

FIG. 6 is a schematic diagram of SIMS of an analytical samplemanufactured according to the present invention;

FIG. 7 shows a result of SIMS according to the present invention;

FIG. 8 shows a result of SIMS of a conventional analytical sample;

FIG. 9 shows a result of SIMS of an analytical sample manufacturedaccording to the present invention;

FIG. 10 shows a result of SIMS of a conventional analytical sample;

FIG. 11 shows a result of SIMS of an analytical sample manufacturedaccording to the present invention; and

FIG. 12 shows a result of SIMS of a conventional analytical sample.

DETAILED DESCRIPTION OF THE INVENTION Embodiment Mode

Hereinafter, an embodiment mode and embodiments of the present inventionare described with reference to the drawings. The present invention canbe carried out in many different modes, and it is easily understood bythose skilled in the art that modes and details can be modified invarious ways without departing from the purpose and the scope of thepresent invention. Accordingly, the present invention should not beinterpreted as being limited to the description of the embodiment mode.

FIG. 1 is a cross-sectional view schematically showing a mode of ananalytical sample manufactured according to the present invention. Theanalytical sample of FIG. 1 includes a supporting body 101, a thin-filmstack body 102, a relief layer 103, and a separation layer 104.

Then, a method of manufacturing the analytical sample shown in FIG. 1 isdescribed with reference to FIGS. 2A to 2D.

First, the separation layer 104, the relief layer 103, and the thin-filmstack body 102 are sequentially formed to be stacked over the substrate105 (see FIG. 2A).

As the substrate 105, a mirror-polished silicon wafer, a glasssubstrate, or the like is used. For a glass substrate, quartz glass,low-melting point glass, or the like may be used. Note that the maximumtemperature which low-melting point glass can withstand is about 700° C.When a glass substrate is used as the substrate 105, a film depositedover a large glass substrate, which may be used for a flat panel displaytypified by a liquid crystal display device, an EL display device, orthe like, can be evaluated.

The separation layer 104 is not particularly limited as long as theseparation layer does not become a contaminant source in an analysisapparatus. The separation layer 104 can be formed using, for example, asemiconductor material like silicon (Si), or a conductive material, suchas tungsten (W), molybdenum (Mo), titanium (Ti), or tantalum (Ta). Asilicon film is preferably used as the separation layer 104. Morepreferably, a silicon film containing fluorine (F) is used. When theseparation layer 104 is formed using a silicon film containing fluorine,separation becomes easy. As such a silicon film containing fluorine, inspecific, a silicon film which contains 1.0×10¹⁷ atoms/cm³ or more and2.0×10¹⁹ atoms/cm³ or less of fluorine (F) is preferably used. Morepreferably, a silicon film containing 1.0×10¹⁷ atoms/cm³ or more and2.0×10¹⁹ atoms/cm³ or less, hydrogen (H) at 1.0×10²¹ atoms/cm³ or moreand 1.0×10²² atoms/cm³ or less of fluorine (F), 1.0×10¹⁵ atoms/cm³ ormore and 2.0×10¹⁸ atoms/cm³ or less of carbon (C), 1.0×10¹⁸ atoms/cm³ ormore and 1.0×10²⁰ atoms/cm³ or less of nitrogen (N), and 1.0×10¹⁵atoms/cm³ or more and 1.0×10¹⁹ atoms/cm³ or less of oxygen is preferablyused. When concentrations are set in the foregoing ranges, separationbecomes easy. Note that, when a film containing a metal element or anorganic substance is used as the separation layer 104, a material whichdoes not or hardly contaminate the insides of an analysis apparatus anda CVD apparatus is used.

The relief layer 103 is formed in order to relieve physical force inseparation of the thin-film stack body 102 which is formed over theseparation layer 104. Conditions for forming the relief layer 103 andthe separation layer 104 can be the same or different. In addition, therelief layer 103 may have a film quality and a film thickness forrelieving the physical force in the separation of the thin-film stackbody 102. When a silicon film with a lower fluorine concentration thanthe separation layer 104 is formed as the relief layer 103, theseparation layer is separated from the substrate, which is preferable.In addition, the relief layer can relieve physical force effectively,which is preferable.

Here, a method of manufacturing the separation layer 104 and the relieflayer 103 using a plasma CVD method is described. FIG. 3 shows onestructural example of a capacitively coupled plasma CVD apparatus. Thecapacitively coupled plasma CVD apparatus 200 shown in FIG. 3 has aprocess chamber 212 including a substrate electrode plate 202, ahigh-frequency electrode plate 204, a gas introducing portion 206, andan exhaust port 208. Note that FIG. 3 shows a mode of the capacitivelycoupled plasma CVD apparatus 200 having four exhaust ports, but thepresent invention is not limited thereto. Note that exhaust ports 208A,208B, 208C, and 208D are collectively referred to as the exhaust port208. The exhaust port 208 is connected to a vacuum pump. Here, theexhaust port 208 is connected to a mechanical booster pump (MBP in FIG.3), the mechanical booster pump is connected to a dry pump (DP in FIG.3), and gas is exhausted though the dry pump. The substrate electrodeplate 202 and the high-frequency electrode plate 204 are arranged inparallel. The substrate electrode plate 202 and the high-frequencyelectrode plate 204 are connected to an AC power source 210, and thesubstrate electrode plate 202 is at a ground potential. Note that animpedance of the capacitively coupled plasma CVD apparatus 200 isadjusted by a matching box. An object to be treated (the substrate 105in FIG. 3) is held by the substrate electrode plate 202. The electricdischarge of the capacitively coupled plasma CVD apparatus 200 iscarried out by the AC power source 210 and plasma is generated betweenthe substrate electrode plate 202 and the high-frequency electrode plate204.

Cleaning is carried out with a fluorine-based gas in a process chamberof the plasma CVD apparatus as shown in FIG. 3. For example, a nitrogentrifluoride (NF₃) gas with a flow rate of 100 SCCM and an argon (Ar) gaswith a flow rate of 50 SCCM are introduced through the gas introducingportion 206 into the process chamber 212 and etching may be carried outunder a pressure of 13 Pa, a substrate temperature of 300° C., and a27-MHz RF oscillator output of 300 W. After the cleaning in the processchamber 212, a separation layer of a silicon film with a high fluorineconcentration is formed by an autodoping method utilizing fluorine 214remaining in the process chamber 212 and successively, a silicon film isdeposited. Thus, the relief layer 103 of a silicon film with a lowfluorine concentration can be formed over the separation layer 104. Forexample, a monosilane (SiH₄) gas with a flow rate of 100 SCCM isintroduced through the gas introducing portion 206 into the processchamber 212 and a silicon film is formed to have a thickness about 500nm under a pressure of 33 Pa, a substrate temperature of 300° C., and a27-MHz RF oscillator output of 170 W. The silicon film thus formed has ahigh fluorine concentration in its lower layer, which is on thesubstrate side, and a low fluorine concentration in its upper layer,accordingly, the lower layer part of the silicon film with a highfluorine concentration serves as a separation layer and the upper layerpart of the silicon film with a low fluorine concentration serves as arelief layer. The formed silicon film includes the separation layerhaving a thickness of about 50 nm and the relief layer having athickness of about 500 nm.

The thin-film stack body 102 may be formed using appropriate single orstacked thin films to be analyzed. For example, a semiconductor filmcontaining silicon or an inorganic semiconductor film, such as an oxidefilm or a nitride film containing silicon oxide, silicon nitride,silicon oxynitride, silicon nitride oxide, or the like is used. Notethat in this specification, when the thin film to be analyzed has asingle layer structure, the thin film is referred to as a thin-filmstack body for convenience.

Note that in this specification, silicon oxynitride refers to asubstance of which larger composition ratio of oxygen is higher thannitrogen, which can be also referred to as silicon oxide containingnitrogen. Similarly, silicon nitride oxide refers to a substance ofwhich larger composition ratio of nitrogen than oxygen, which can bealso referred to as silicon nitride containing oxygen.

As shown in FIGS. 4A to 4C, a lower layer of a film to be analyzed mayalso serve as a relief layer. An analytical sample shown in FIG. 4A hasa separation layer 306 formed over a substrate 308 and a film 304 to beanalyzed over the separation layer 306. A lower layer of the film 304 tobe analyzed may serve as a relief layer. For example, a silicon film isformed as the film 304 to be analyzed, a region 310 doped with animpurity element by doping is formed in the film 304 to be analyzed (seeFIG. 4B), and a supporting body 302 having an adhesive property isattached so that separation is carried out (see FIG. 4C). Thus, thedepth which the impurity element reaches in the silicon film when thesilicon film is doped with the impurity element can be detected.Further, according to the present invention, information about thesubstrate which is detected in a method in which a rear surface of asubstrate is polished and the polished surface is irradiated withprimary ions for SIMS analysis is not detected, so that a crater edgeeffect can be reduced; accordingly the dose and the like of the impurityelement can be evaluated with excellent accuracy.

Then, an opening portion 106 is formed in the separation layer 104, therelief layer 103, and the thin-film stack body 102 which are stackedover the substrate 105 (see FIG. 2B).

Note that the opening portion 106 may be formed by, for example, makinga cut using a physical means (e.g., laser, a sharp item like a cutter).When the opening portion 106 is formed in the separation layer 104, therelief layer 103, and the thin-film stack body 102; the thin-film stackbody 102, which is to be an analytical sample can be easily peeled offfrom the substrate.

Then, an adhesive surface of the supporting body 101 is attached to asurface of the top layer of the thin-film stack body 102. The supportingbody 101 is attached to cover the opening portion 106 partially orentirely (see FIG. 2C).

The supporting body 101 uses a material with high thermal resistancewhich does not contaminate the inside of the SIMS apparatus, which iskept in high vacuum or ultra-high vacuum, to an extent that ananalytical result is affected by contamination. In analysis by SIMS, inorder to prevent electrification (charge build-up) due to irradiationwith primary ions to the analytical sample in analysis, a neutralizationgun (e.g., an electron gun emitting electrons) which emits charge withopposite polarity with respect to charge of the electrification may beused and emit charge. At this time, the temperature of the analyticalsample may rise by being heated due to irradiation by a neutralizationgun; accordingly, the thermal resistance of the supporting body 101refers to thermal resistance which makes the supporting body 101withstand that rise in temperature. In addition, since the analyticalsample may be heated due to irradiation by the neutralization gun or thelike in analysis as described above, the supporting body 101 having onesurface provided with an adhesive of which contamination does not affectthe analytical result is necessarily selected in consideration of therise in temperature due to the heating. In the supporting body 101,polyimide, a Kapton® film, or the like can be used as a base materialand a silicone-based adhesive can be used as the adhesive. A Kapton®tape is preferably used as the supporting body 101.

FIGS. 5A and 5B each show a top view of FIG. 2C. FIG. 2C corresponds toa cross-sectional view taken along the line OP in each of FIGS. 5A and5B. In FIGS. 5A and 5B, the relief layer 103, the separation layer 104,and the substrate 105 are provided below the thin-film stack body 102 asshown in FIG. 2C. The thin-film stack body 102 has the opening portion106 and the supporting body 101 is attached to cover the opening portion106. Note that the supporting body 101 is not necessarily formed overthe entirely over the thin-film stack body 102 and the opening portion106, but the supporting body may be attached to cover the entire openingportion 106 as shown in FIG. 5B. It is preferable that the supportingbody 101 is attached so as not to cover the entire opening portion 106and to expose the opposite ends of the opening portion 106 as shown inFIG. 5A. When the supporting body 101 is attached as shown in FIG. 5A,separation can be carried out smoothly.

Next, the separation layer 104, the relief layer 103, the thin-filmstack body 102, and the supporting body 101 are separated from thesubstrate 105 (see FIG. 2D). In the foregoing manner, an analyticalsample having a stack body including the separation layer 104, therelief layer 103, the thin-film stack body 102, and the supporting body101, which are separated from the substrate 105, is obtained.

Note that in the separation of the analytical sample from the substrate105, when the supporting body 101 is peeled off using the preformedopening portion 106 as a start, the separation can be carried out at theinterface between the separation layer 104 and the substrate 105 whichserves as a boundary without a complicated step. The supporting body 101after the separation has the separation layer 104, the relief layer 103,and the thin-film stack body, which are transferred to the supportingbody 101 from the substrate 105 where they are formed before theseparation. Note that since the analytical sample is separated with theseparation layer 104 serving as a boundary, the separation layer 104transferred to the supporting body may be partially thin.

In the foregoing manner, the analytical sample can be manufactured whichhas a stacked body including the supporting body 101, the thin-filmstack body 102, the relief layer 103, and the separation layer 104.

Next, a method of analyzing the analytical sample manufactured accordingto the present invention is described. FIG. 6 shows a schematic diagramof SIMS. In a schematic diagram showing a state of SIMS, a SIMSapparatus includes an ion source 401, a detector 402, and aneutralization gun 403. A surface of an analytical sample 404 issputtered with primary ions 405 emitted from the ion source 401, andsecondary ions 406 are generated from the surface of the analyticalsample. The detector 402 detects the secondary ions 406, so that theanalytical sample 404 manufactured according to the present inventioncan be analyzed.

The ion source has a structure in which cesium ions (Cs⁺) are generatedby heating a tank including solid cesium by a heater. Cesium ions (Cs⁺)which are the primary ions 405 are electrically accelerated and collidewith the analytical sample 404, so that the secondary ions 406 aregenerated. The secondary ions 406 include a large amount of neutralparticles, a small amount of cations, and a small amount of anions. Whenthe secondary ions 406 include elements which are generally calledatmospheric components, such as hydrogen, carbon, nitrogen, oxygen, orfluorine, the anions are introduced into the detector 402, and a traceamount of impurities contained in the analytical sample 404 is detectedby a quadrupole mass spectrometer in the detector 402.

The neutralization gun 403 is an electron gun to prevent charge build-up(electrification) of the analytical sample 404 due to irradiation withthe primary ions 405 and to neutralize the analytical sampleelectrically. The neutralization gun is used to irradiate a regionirradiated with the primary ions 405 in the surface of the analyticalsample 404 with charge having opposite polarity with respect to chargeof the electrification. The use of the neutralization gun 403 canprevent charge build-up of the analytical sample 404. In addition, inthe case in which the analytical sample 404 is directly on an insulatingsubstance, such as a glass substrate or an organic substance (e.g., atape), generation of charge build-up can be prevented and the secondaryions 406 can be generated stably.

The analytical sample 404 has a stacked layer structure in which theseparation layer 104, the relief layer 103, and the thin-film stack body102 are stacked over the supporting body 101. As shown in FIG. 6, theseparation layer 104 is irradiated with the primary ions 405 andsputtered; then, the secondary ions 406 are detected. In other words, inthe analytical sample 404, the composition of a film is analyzedsequentially from the separation layer 104. Since the thickness of theseparation layer is extremely small compared with that of the substrate,the affect of the crater edge effect and the like is negligibly small.

As described above, according to the present invention, a rear surfaceof a sample can be emitted with primary ions without polishing asubstrate. Therefore, concentration distribution of an impurity can beanalyzed highly precisely without complicated steps. In other words,analysis of an impurity in the depth direction can be carried out highlyprecisely without a step of polishing the substrate.

According to the present invention, in the case in which an impurity isdistributed at a high concentration in a surface of the top layer ofthin films, for example, when the impurity is added with ion doping byion injecting apparatus, impurity analysis can be carried out withexcellent accuracy from a lower layer of the thin films, which is aregion where the impurity is distributed at a low concentration.

Embodiment 1

A result of analysis of concentration distribution in the depthdirection by SIMS according to the present invention is described.

FIG. 7 shows a result of analysis (profile) of a sample A by SIMS, whichis manufactured according to the present invention. The sample A has asimilar structure to that of the analytical sample 404 described inEmbodiment Mode, in which a thin-film stack body to be analyzed, arelief layer, and a separation layer are sequentially stacked over aKapton® tape used as a supporting body having an adhesive property. Inthe sample A, the separation layer 104 side is irradiated with primaryions and the sample A is analyzed by SIMS. Note that the sample A isadhered to a stage and firmly fixed so that the sample A is not deformeddue to heat generated by a neutralization gun (e.g., electron gun).

In this embodiment, a Kapton® tape refers to a tape in which a Kapton®film is used as a base material and a silicone-based adhesive is used asan adhesive, which is, for example, used as a masking tape in solderingof a printed board.

FIG. 8 shows a result of analysis (profile) of a sample B by SIMS, whichis a comparative example. The sample B has a similar structure to thestacked layer structure described in Embodiment Mode, with reference toFIG. 2A in which a separation layer, a relief layer, and a thin-filmstack body are stacked in this order over a glass substrate. In thesample B, the thin-film stack body side (a surface side of the toplayer) is irradiated with primary ions and the sample B is analyzed bySIMS. Note that the sample A has a structure in which a supporting bodyhaving an adhesive property is attached onto the thin-film stack bodywhich is formed through the same steps as those of the sample B, so thatthe thin-film stack body is transferred. Accordingly, the sample A hasthe separation layer, the relief layer, and the thin-film stack bodywhich are the same as those of the sample B.

In SIMS of the sample A and the sample B, elements to be measured aresilicon, hydrogen, carbon, nitrogen, oxygen, and fluorine. Note that inFIGS. 7 and 8, silicon, hydrogen, carbon, nitrogen, oxygen, and fluorineare denoted by Si, H, C, N, O, and F, respectively. In each of FIGS. 7and 8, the horizontal axis indicates the depth from an irradiationsurface and the vertical axis indicates the ionic strength.

In FIG. 8, the ionic strength of silicon is stable at about 5×10⁴counts/second.

In FIG. 7, the ionic strength of silicon is stable at about 8×10⁴counts/second. That is, the ionic strength of silicon in FIG. 7 isstable at almost the same degree as that in FIG. 8.

The comparison between FIGS. 7 and 8 reveals that in the case to whichthe present invention is applied (the case of carrying out separationshown in FIG. 7), analysis can be carried out similarly to the case towhich the present invention is not applied (the case without separationshown in FIG. 8).

Embodiment 2

Concentration distributions in the depth direction are analyzed by SIMSin a sample in which separation is carried out according to the presentinvention and a sample in which separation is not carried out, and thencompared. The result is described below.

An analytical result of a silicon film doped with boron (B) as animpurity element is described. FIG. 9 shows a result of analysis(profile) of a sample C by a SIMS, which is manufactured according tothe present invention. The sample C has a similar structure to that ofthe analytical sample 404 described in Embodiment Mode, in which siliconfilms formed as a thin-film stack body to be analyzed and a relieflayer, and a silicon film containing fluorine formed as a separationlayer are stacked in this order over a Kapton® tape which is used as asupporting body having an adhesive property. The silicon films formed asa thin-film stack body to be analyzed and a relief layer are doped withboron (B). In the sample C, the separation layer side is irradiated withcesium (Cs⁺) as primary ions and the sample C is analyzed by SIMS. Notethat the sample C is adhered to a stage and firmly fixed so that thesample C is not deformed due to heat generated by a neutralization gun(electron gun).

In this embodiment, a Kapton® tape refers to a tape in which a Kapton®film is used as a base material and a silicone-based adhesive is used asan adhesive, which is, for example, used as a masking tape in solderingof a printed board.

FIG. 10 shows a result of analysis (profile) of a sample D by SIMS,which is a comparative example. The sample D has a similar structure tothe stacked layer structure in FIG. 2A described in Embodiment Mode inwhich a separation layer, a relief layer, and a thin-film stack body arestacked in this order over a glass substrate. In the sample D, thethin-film stack body side (a surface side of the top layer) isirradiated with cesium (Cs⁺) as primary ions and the sample D isanalyzed by SIMS. Note that the sample C has a structure in which asupporting body having an adhesive property is attached onto thethin-film stack body which is formed through the same steps as those ofthe sample B, so that the thin-film stack body is transferred.Accordingly, the sample C has the separation layer, the relief layer,and the thin-film stack body which are the same as those of the sampleD. Each of the samples C and D are analyzed with acceleration voltage of3 kV and current density of 100 nA.

In SIMS of the sample C and the sample D, elements to be measured areboron, silicon, and fluorine. Note that in FIGS. 9 and 10, boron,silicon, and fluorine are denoted by B, Si, and F, respectively. As toboron, both ¹¹B and ¹⁰B, which is an isotope thereof, are detected. Notethat in each of FIGS. 9 and 10, the horizontal axis indicates the depthfrom an irradiation surface and the vertical axis indicates the ionicstrength.

In comparison between FIGS. 9 and 10, ionic strength is graduallychanged at the interface between the silicon film and the silicon filmdoped with boron in FIG. 10, whereas the ionic strength is drasticallychanged at the interface in FIG. 9, which clearly shows the position ofthe interface.

Further, FIGS. 11 and 12 show results of analyses (profiles) by SIMS ofboron (B) in the samples C and D to which O₂ is used as primary ionsemitted thereto. In FIG. 12, the boron concentration is graduallychanged at the interface between the silicon film and the silicon filmdoped with boron as in FIG. 10. In FIG. 11, the boron concentration isdrastically changed at the interface as in FIG. 9, which clearly showsthe position of the interface.

In the comparison between FIGS. 9 and 10, and between FIGS. 11 and 12,it is considered that since the sample D is analyzed from the thin-filmstack body side, boron elements on the periphery are detected due to thecrater edge effect, so that the position of the interface between thesilicon film and the silicon film doped with boron becomes unclear. Onthe other hand, it is also considered that since the sample C to whichthe present invention is applied is analyzed from the separation layerside, the sample C can be analyzed with excellent accuracy as in amethod in which a rear surface of a substrate is polished and thepolished surface is irradiated with primary ions for analysis by SIMS;accordingly, the position of the interface between the silicon film andthe silicon film doped with boron becomes clear in the data of theanalytical result.

As described above, according to the present invention, a SIMS samplecan be easily manufactured and the sample can be analyzed highlyprecisely as in a method in which a rear surface of a substrate ispolished and the polished surface is irradiated with primary ions foranalysis by SIMS. In other words, the concentration distribution in thedepth direction can be analyzed more precisely.

This application is based on Japanese Patent Application serial no.2006-296745 filed in Japan Patent Office on Oct. 31, 2006, the entirecontents of which are hereby incorporated by reference.

1. A method of manufacturing an analytical sample by a secondary ionmass spectrometry method, comprising: forming a separation layercomprising an amorphous silicon film containing fluorine over a glass asubstrate; forming a relief layer comprising an amorphous silicon filmcontaining fluorine over a separation layer; forming one of a thin filmand a thin-film stack body to be analyzed over the relief layer; formingan opening portion in one of the thin film and the thin-film stack body;attaching a supporting body to one of a surface of the thin film and asurface of a top layer of the thin-film stack body; peeling off one ofthe thin film and the thin-film stack body from the glass substrate; andwherein the separation layer is a film with a higher fluorineconcentration than the relief layer.
 2. The method of manufacturing ananalytical sample according to claim 1, wherein the opening portion isformed by a physical means.
 3. The method of manufacturing an analyticalsample according to claim 1, wherein the supporting body includes a basematerial and an adhesive over a surface of the base material, andwherein the adhesive contains organopolysiloxane.
 4. The method ofmanufacturing an analytical sample according to claim 1, wherein theseparation layer is a film with a fluorine concentration of 1×10¹⁷atoms/cm³ or more and 2×10¹⁹ atoms/cm³ or less, a hydrogen concentrationof 1×10²¹ atoms/cm³ or more and 1×10²² atoms/cm³ or less, a carbonconcentration of 1×10¹⁵ atoms/cm³ or more and 2×10¹⁸ atoms/cm³ or less,a nitrogen concentration of 1×10¹⁸ atoms/cm³ or more and 1×10²⁰atoms/cm³ or less, and an oxygen concentration of 1×10¹⁵ atoms/cm³ ormore and 1×10¹⁹ atoms/cm³ or less.
 5. The method of manufacturing ananalytical sample according to claim 1, wherein the relief layer is afilm with a fluorine concentration of 1×10¹⁷ atoms/cm³ or more and2×10¹⁹ atoms/cm³ or less, a hydrogen concentration of 1×10²¹ atoms/cm³or more and 1×10²² atoms/cm³ or less, a carbon concentration of 1×10¹⁵atoms/cm³ or more and 2×10¹⁸ atoms/cm³ or less, a nitrogen concentrationof 1×10¹⁸ atoms/cm³ or more and 1×10²⁰ atoms/cm³ or less, and an oxygenconcentration of 1×10¹⁵ atoms/cm³ or more and 1×10¹⁹ atoms/cm³ or less.6. A method of analyzing an analytical sample by a secondary ion massspectrometry method, comprising: forming a separation layer comprisingan amorphous silicon film containing fluorine over a glass substrate;forming a relief layer comprising an amorphous silicon film containingfluorine over a separation layer; forming one of a thin film and athin-film stack body to be analyzed over the relief layer; forming anopening portion in one of the thin film and the thin-film stack body tobe analyzed; attaching a supporting body to one of a surface of the thinfilm and a surface of a top layer of the thin-film stack body; peelingoff one of the thin film and the thin-film stack body from the glasssubstrate; irradiating a surface of the separation layer with primaryions to analyze one of the thin film and the thin-film stack body; andwherein the separation layer is a film with a higher fluorineconcentration than the relief layer.
 7. The method of analyzing ananalytical sample according to claim 6, wherein the opening portion isformed by a physical means.
 8. The method of analyzing an analyticalsample according to claim 6, wherein the supporting body includes a basematerial and an adhesive over a surface of the base material, andwherein the adhesive contains organopolysiloxane.
 9. The method ofanalyzing an analytical sample according to claim 6, wherein theseparation layer is a film with a fluorine concentration of 1×10¹⁷atoms/cm³ or more and 2×10¹⁹ atoms/cm³ or less, a hydrogen concentrationof 1×10²¹ atoms/cm³ or more and 1×10²² atoms/cm³ or less, a carbonconcentration of 1×10¹⁵ atoms/cm³ or more and 2×10¹⁸ atoms/cm³ or less,a nitrogen concentration of 1×10¹⁸ atoms/cm³ or more and 1×10²⁰atoms/cm³ or less, and an oxygen concentration of 1×10¹⁵ atoms/cm³ ormore and 1×10¹⁹ atoms/cm³ or less.
 10. The method of analyzing ananalytical sample according to claim 6, wherein the relief layer is afilm a with a fluorine concentration of 1×10¹⁷ atoms/cm³ or more and2×10¹⁹ atoms/cm³ or less, a hydrogen concentration of 1×10²¹ atoms/cm³or more and 1×10²² atoms/cm³ or less, a carbon concentration of 1×10¹⁵atoms/cm³ or more and 2×10¹⁸ atoms/cm³ or less, a nitrogen concentrationof 1×10¹⁸ atoms/cm³ or more and 1×10²⁰ atoms/cm³ or less, and an oxygenconcentration of 1×10¹⁵ atoms/cm³ or more and 1×10¹⁹ atoms/cm³ or less.